1. Field of the Invention
The present invention relates generally to hard copy sheet processing apparatus used in various automated business machines. More specifically, it is concerned with apparatus for quickly changing the flow direction of successive sheets of print media (such as paper) before they are fed to another workstation in that same machine, or to an altogether different machine.
2. Description of Related Art
Automated business machines for producing or reproducing hard copy documents (such as inkjet printers, electrophotographic printers, impact printers, copiers, facsimile machines, document scanners and the like) often include, or are otherwise associated with, a mechanism that changes the flow direction or path over which a sheet of print media travels through a given automated business machine. Those skilled in the automated business machine arts also will appreciate that such sheet flow direction changes are made for several reasons. For example they are often made to invert the stacking sequence of a series of sheets. This causes the first side of a first sheet to be the first or xe2x80x9ctopxe2x80x9d side of the first printed sheet (and so on for the second, third, etc. sheets) when a stack is removed from a collection tray and turned over. Otherwise, the order of the sheets in the stack would have to be reversed. This is a time consuming operation. Sheet flow direction changes also are employed to reduce the xe2x80x9cfootprintxe2x80x9d of a given machinexe2x80x94especially in a desktop working environment. Other automated business machine operations change a sheet""s flow direction in order to send that sheet to an entirely different machine or to send that sheet to a sheet collection tray located inside or outside of the machine in which the sheet flow direction is changed.
The sheet flow direction changing mechanisms of this patent disclosure address the sheet turnover time and machine xe2x80x9cfootprintxe2x80x9d problems by providing a mechanically simple, fast acting mechanism that takes less lateral space and less vertical space relative to various prior art sheet flow direction changing devices. Because of their relatively faster actionsxe2x80x94and smaller space requirementsxe2x80x94applicant""s sheet flow direction changing mechanisms are more readily associated with various automated business machines such as inkjet printers, electrophotographic printers, impact printers, copiers, facsimile machines, document scanners and the like. These mechanisms also are characterized by their mechanical simplicity and, hence, reliability. Applicant""s sheet flow direction changing mechanisms are preferably used in those automated business machines that process sheets of print media, such as sheets of paper, that are flexible in nature. Those skilled in this art will appreciate that other flexible (i.e., capable of being bent or buckled in a manner hereinafter described), sheet-like, materials (such as thin sheets of flexible polymer compositions) can be processed by the mechanisms described in this patent disclosure while other more rigid (and hence relatively inflexible) materials (such as thicker sheets of inflexible polymer compositions) may not be so readily processed.
The two most important components of applicant""s sheet flow direction changing mechanism are a three roller device and a sheet flow stopping device. The three roller device is comprised of a first roller (e.g., a center roller), a second roller (e.g., a top roller) and a third roller (a bottom roller). These three rollers form first and second rolling interface contact regions hereinafter more fully described. The three roller device first operates by driving a sheet in a first flow direction (e.g., rightward) by virtue of being driven between the interface of the first roller (e.g., the center roller) and the second roller (e.g., the top roller). The sheet flow stopping device serves to stop this sheet flow in the first direction and to position the trailing edge of such a sheet with respect to another roller interface of the first roller (e.g., the center roller). This other interface is between the first roller (e.g., center roller) and a third roller (e.g., the bottom roller) of said three roller device. The trailing edge of the sheet is then fed into this other interface and thereby changing the sheet""s flow direction.
The sheet flow direction changing mechanisms of this patent disclosure are particularly characterized by the fact that they are, to a very large degree, mechanical in nature. That is to say that they operate primarily through mechanically connected elements (such as linkage arms) rather than through use of electrical signals to those mechanical elements. Hence, the hereindescribed sheet flow direction changing elements are generally less complex, more reliable and less costly than those sheet flow direction changing devices that employ various electrical sensing and signaling devices to control their sheet handling components.
Optionally, the sheet flow direction changing mechanism of this patent disclosure may further comprise (1) an automated sheet flow stopping device that is mechanically operated by an incoming sheet of print media, (2) one or more sheet guide plates that mechanically direct the trailing edge of a sheet of print media into a roller nip between the center roller and the bottom roller of the three roller device of the sheet flow directing mechanism and (3) a mechanical linkage mechanism that operates a foot-like sheet stopping device in a manner that serves to fix a sheet under the foot-like sheet stopping mechanism in a position such that the trailing edge of that stopped sheet will come into friction contact with the outside surface of the center roller and thereby driving that trailing edge downward in a manner such that a sheet bends, buckles or humps in a way that is conducive to feeding the trailing edge of the sheet into a nip between the center roller and bottom roller.
Subsequent parts of this patent disclosure will demonstrate how a sheet of flexible print media such as paper will naturally unbuckle after it is driven downward and past the center roller. Such a sheet will then unbuckle in a an opposing (e.g., leftward) direction because its other side is held down by a sheet stopping device. The passage of the sheet between the center roller and bottom roller drives the sheet in a flow direction that is, to some degree, the opposite direction from that in which the sheet was driven as it passed between the center roller and top roller. In some still more preferred embodiments of this invention, applicant""s sheet flow direction changer apparatus will further comprise a sheet turnover device. Since roller type sheet turnover devices are so commonly used, they will be used as the primary example of those sheet turnover or xe2x80x9cflippingxe2x80x9d devices for the purposes of this patent disclosure.